This invention relates to fluid photo reactors and more particularly to ultraviolet ray (UV) water purifiers.
In a typical irradiation type of water purifier, a quartz tube or sleeve which is circular in cross section containing the source of UV is mounted in the path of flowing water to be purified. The UV passes through the transparent wall of the sleeve and effects the elimination of bacteria, mold, virus, and algae from the water.
The use of UV for the disinfection of water has been accepted by the U.S. Public Health Service provided the equipment used meets certain listed criteria. Among the criteria listed is a specified minimum dosage of the UV and the use of equipment which includes provision to permit frequent mechanical cleaning of the water contact surface of the sleeve without disassembly of the unit. Thus, some provision must be incorporated to permit frequent cleaning of the outer surface of the quartz sleeve.
To meet the aforementioned requirement, one popular design of such a unit incorporates wiper assemblies mounted on the outside of the quartz sleeve with a rod extending outside of the unit for reciprocating the wiper assemblies periodically to clean the surface. The assemblies generally employ wiper rings which surround the quartz sleeve snugly so that movement along the length of the sleeve will result in cleaning of the surface. Some current designs for supporting the wipers are generally difficult to fabricate on an assembly line basis, and often require frequent repair and maintenance.
In addition, the quartz tubing in use is not perfectly round nor perfectly straight. For example, commercial tolerance of the outside diameter is commonly plus or minus 4% and the tube is most often out of round. Quartz tubes used in ultraviolet water purfiers now often exceed 60 inches in length and they often exhibit varying degrees of bow along the length. One consequence of the foregoing is that in typical wiper arrangements now in use there may be hit and miss contact between the wiper and the outer surface of the tube.
The following U.S. patents show present designs of irradiation devices including various ways of cleaning the surface of the transparent sleeve: U.S. Pat. Nos. 3,061,721, 3,462,597, 3,562,520, and 3,904,363. A current design is also shown in Pollution Engineering, December 1973, Ultraviolet Water Purification, by J. G. Mone, FIG. 3. None of the preceding patents or publications teaches the present invention.